h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I've been doing biodiversity research for much of my life, and can confidently say, the average person doesn't have the first beginning of a glimmer of a clue of the diversity that's out there on Planet Earth.

If I tell people for instance that there are about 10 000 species of birds known from all over the planet ... people will not have the first clue as to just how spectacular a diversity that is. Most people know perhaps a dozen or so species of birds. I'm lucky to live in a country where there are close to 1 000 bird species but I've seen only about 300 or 400 of them. But I've devoured all bird books I could get my hand on from a very young age, I've been looking on the 'net, I've started collecting a series of guides to all the birds in the world ... and I'm only just starting to realise just how many of them there are and what amazing kinds there are.

Then there are mammals ... most people know cats, dogs, horses, and some zoo mammals ... but there are thousands of incredibly obscure mammal species all over the world ... many of them known just about not at all, we merely have an old dusty skin in a museum somewhere to remind us that this species has indeed been 'collected, classified and catalogued'. But we know nothing of its lifestyle and often, nothing even about its appearance in life.

When it comes to reptiles and amphibians, people know just about nothing. People think in terms of 'lizards' or 'snakes' or 'turtles' ... whereas there are over 8 000 known reptile species and *indubitably* many more awaiting discovery. The diversity is once again staggering ... when thinking only of 'lizards' ... they go from almost microscopically tiny geckoes and dwarf chameleons, to the giant komodo dragons, and there are so many utterly weird kinds such as the Australian frilled dragons, or the South American basilisks that can run on water ... my own faves are the chameleons, that are absolutely incredibly 'modified' to suit their lifestyles ... literally every part of their bodies have been changed from the 'normal' lizard condition: their tails can now grip and curl into a spiral; their little 'fingers' and 'toes' have become encased in little mitts to become twig-grasping 'pliers' ... their bodies have become tall and narrow, rather than flat ... their heads have developed (in most species) erectable crests at the rear ... most species have erectable throat flaps as well ... their eyes are raised in little 'turrets' and can swivel backward and forward independently ... they have those incredible tongues they can shoot out ... and last but not least, the ability to change colour ... and different colours and patterns in different species. (Chameleons use colour change more for display than for camouflage.) And ... there are over 150 species of them ... and *most* of those - and the most amazing ones - are confined to the island of Madagascar, the Nature of which is being ravaged beyond belief, by humans!

Now if people can just start having an appreciation for the exquisiteness of chameleons ... just for a start ... how wonderfully something as simple as a lizard has become modified ... this can be a start, just a *start*, in realising just how wonderful Nature is and what incredible potential there is ... evolutionary potential, potential for different kinds of shapes and ways of being, for living things.

Then amphibians ... 'frogs and toads' mostly ... but what incredibly wonderful ones! The simplicity of the 'frog' bodyplan ... a little creature that has elongated hind legs so it can hop at split second notice, either towards a tasty tidbit, or away from a potential predator. This simple 'plan' has become diversified into over 5 000 known species ... and again, the average person has no clue about the diversity. Frogs that spend their whole lives in water ... burrowing frogs that survive even in the desert ... tree frogs ... and their amazing abilities: frogs that make 'mud cocoons' in which they can surive dry periods for years ... frogs that brood their young in their *stomachs* ... and the tiny arrow-poison frogs, as remarkable for their beauty and bright colours, as for the extremely virulence of their poison ... and more.

And frogs are amongst the hardest-hit groups of all ... extinctions happening all over the world ... and the stomach-brooding frogs are *all* extinct now ... a 'way of life' that no longer exists!

Salamanders, while less diverse than the frogs, are equally delightful ... and then there are the limbless caecilians ... looking very much like earthworms, but still, vertebrates!

Then there's the diversity of *swimming* vertebrates ... bony fishes, sharks and rays ... few people realise it, but sharks and rays are only distantly related to bony fishes. You and I are more closely related to a tuna, than a shark is!

Marine as well as freshwater fish diversity is incredible. All land vertebrates taken together, don't match them ... about 30 000 known species of bony fishes! Most of them in the sea ... but there are also remarkable centres of freshwater fish diversity, such as the Amazon River with about 2 500 known species ... which is mind-blowingly incredible! That's more fish species in one river system, than there are bird species in all of Africa (about 2 100). In Africa, there is spectacular diversity in the Lakes of the Rift Valley such as Lake Malawi - with several *hundred* species of Cichlid fish in it ... all of which evolved since the relatively recent creation of the lake *at most* two million years ago (geologically, that's a very short time ... our own forebears were already recognisably human 3 to 4 million years ago).

Sharks and rays - the cartilage-skeletoned fish - number about a thousand, so the diversity is less than in the bony fishes ... but they are a link with the Earth's ancient past, being 'around' almost unchanged for over 300 million years ... and there is quite a lot of diversity in their shapes and lifestyles. And much weirdness like the Goblin shark, or the Megamouth shark.

Fishes worldwide are under enormous pressure ... basically, because *we* eat them! In freshwater there are added pressures like pollution, dam creation, and the release of species into rivers or lakes where they are not native and end up eating up the native species.

So: there you have a quick overview of vertebrate diversity. I can't even begin describing the diversity of invertebrates! It is staggering though ... the estimation of the number of *insect species* worldwide, go from about 5 million to over 80 million ... *each one* of which is unique! But ... we have so far only named about 1 million species, and of those, we know just about nothing about most.

I will maybe soon write something about invertebrate animals ...

But what about plants?

You'll know I am very interested in plant life ... not only because plants on land and in water support the entire ecosystems and make it possible for the animals to eat and live ... but because they are wonderful and fascinating in their own right. And also, for a Nature lover ... plants are much more accessible! They don't run away ... you can walk right up to them, study them, touch them, smell them, and in some cases, taste them ... you can visit them in different seasons, in each of which they look different ... you can go and collect seeds from them, and grow their offspring yourself and study them as they develop - what a wonderful privilege!

So ... plant diversity ... we know about 350 000 species of land plants ... which is incredible! They range from tiny algae to huge redwoods and sequoias ... the largest living beings. I can't begin here to try and suggest the kind of diversity that exists in plants. I can mention certain features, though: there are 'hot spots' of extreme plant diversity in the world. Some regions have very low diversity ... sad to say, northern and western Europe is such a region. There are comparatively few species, and especially, low levels of 'endemism' - plants found in some areas and nowhere else. But in some areas, such as the rainforests of South and Central America - or Southeast Asia, and the islands of Indonesia, there is huge diversity and also large levels of endemism - plants found only in small areas.

Plant diversity is not high only in rainforest regions. In the summer-dry shrublands of Southwestern South Africa, there's an incredible number of species of shrubs and small flowering plants. There are also dry and desert areas with large numbers of specially-adapted plants. Such desert plant hot-spots include the regions around the Namib Desert in South Africa, and the horn of Africa - mainly, Somalia and parts of Ethiopia, and also including bits of Kenya.

With plants the major thing is - you get 'special wonder worlds' defined by the unique plants that make them up. Such as the Quiver Tree Forests of parts of South Africa ... the 'Giant Groundsel' Afromontane heaths of the high East African mountains ... the 'Polylepis forests' of the high Andes mountains of South America (the highest-growing tree in the world) ... the cushion plants, the giant herbs, and Kauri forests of New Zealand ... the temperate rainforests of Chile ... the monkey puzzle forests of temperate-southeast South America ... and so many others! In each case ... a very characteristic kind of plant, or group of plants, grow in just one particular region of the world ... and they impart to that region, a totally unique 'style' - a look, a feel, a spirit, a 'personality'!

So ... with the absolutely incredible destruction humanity has wrought on the plant-life of the world ... so much of the *uniqueness of places* has been lost! And not only that ... plant species have been and are being lost ... and the thing is this ... we know little about plant evolution and relationships. There are signs that this process is extremely complex in plants ... they hybridise with each other to a much greater extent than animals do. Also, with plants, you have so many features of the *environment* determining how the fully grown plant looks ... closely related species may look very different because of growing in very different environments. Then, we have the phenomenon of gene transfer even between plants that are not closely related. All in all ... plant evolution and diversification is an extremely complex phenomenon about which we know very little ... and, if we could study it, would tell us so much about how Nature works.

And in this ... every single species of plant ... in its natural population ... is, for us, a clue, a clue to Evolution, a clue to how plants are related to each other, a clue to how they spread over the world and came to inhabit specific places, a clue the whole interplay between genes and environment ... relevant to US as well! But now ... we are destroying these clues! With our destruction of plant species and populations ... we are erasing pages and pages of the 'Book of Knowledge of Nature'!!!

What people also should know is that this mind-boggling diversity of things that exist now ... is just a 'snapshot' of the diversity of living things that used to exist on Planet Earth. Everything alive has a *history* - and for most species, that history is incredibly complex. As weird and fantastic as some living things are ... there have been living things even weirder, that are no longer with us. Once we start researching extinct creatures ... another new world opens up to our eyes! And - the extinct creatures we know, are only the ones of which we have discovered the fossils ... there are so many more, that either didn't become fossils, or that we haven't found yet. But ... the diversity of *known* extinct species, goes far beyond the diversity we see in living species.

One more thing people should know is that the biodiversity of the planet right now is *impoverished* compared to some other periods. We have gone through the traumatic and frequent climate shifts of the Ice Ages, as well as the ravages of humanity, the two together having already exterminated many species over the past 10 000 years or so. Currently, the diversity of large mammals is only half of what it was in some other periods such as the Pliocene, just before the Ice Ages.

Plant diversity has also been affected. The Ice Ages have progressively scoured the northern continents with glaciers, progressively eliminating species. After every ice age, warm-climate plants returned, but each time, less than before. Previous to the Ice Ages, Europe and northern North America had a very much more diverse vegetation, including many species now only known in the tropics and subtropics.

But humans, too, have played an enormous role in destroying species of animal and plant. It's difficult to know if we exterminated species like the mammoths and sabre-tooth tigers in our distant past ... we *might have contributed significantly* to their extinctions, along with climate change. But we *do* know that humans *have* exterminated a vast diversity of animals - mammals, and also birds - from their native regions in the more recent past. Entire holocausts of native faunas have happened in places like the Pacific Islands, or Indian Ocean islands like Madagascar and the Mascarenes. In the Pacific Islands, the number of bird species exterminated, is estimated between 750 and 1 200 species. They include entire families gone extinct, like the Sylviornithids of New Caledonia, and the Moas and Adzebills of New Zealand. These birds were mostly flightless - having had no reason to maintain flight ability in the peaceful ecosystems of those islands. In many cases, mammals brought by humans - pigs, rats, cats, mongooses - have done the actual work of extermination.

On Madagascar, incredibly wonderful mammals have also been rendered extinct ... about half of the lemur species, including the biggest ones, as large as gorillas. We will never know what they looked like, or how they lived.

In some cases all we have left are bones ... sometimes we have skins ... for some species recently gone extinct, we have photos ... but we don't have the living things any more, we can't look at them and the way they live, the way they fit into their environments, their interactions with everything else, any more.

The World we Never Knew - the world before humans - must have been amazing ... if we could be transported back then by a time machine, and freely explore, we would see so many things that are no longer around ... worlds of wonder, scenery undreamt of, with plants looking like nothing we know, and strange beasts lumbering around. We would find many small wonder-worlds as well, when we explore the islands - much more uniqueness than what we have left now, since islands back then really *were* islands, separate, each - with its entire web of life - going its own way.

Even the world we have now - we know so little about.

And we are rapidly turning it into a wasteland.

Do we want our progeny to think back longingly about the World that Almost Was - a world in which we humans *could have* protected and nurtured the wonder of Nature that they had - still - the ability to preserve?

Oh Willem!

How beautifully written.

How icredibly sad.

Thank you for writing it so sensitively.

With much affection

Christiane

Tuesday 8/XII/2009 13.10 GMT

I will have a read of this shortly .

Thank you my friend.

Nigel

Hello Christiane AR80 and Nigel and thanks for reading! I think I'll write some follow-up pieces, about specific aspects mentioned in this 'article' ... might as well call it an article!